The shocking truth about solar eruptions

7 October 2013

The Sun gives light and heat that makes life possible on
Earth. That said, our nearest star can have more sinister effects, sometimes
unleashing huge eruptions of hot gas, called coronal mass ejections (CMEs),
which carry billions of tons of matter travelling at millions of kilometres an
hour into space. These storms can be accompanied by solar radio bursts, and if
they head in Earth’s direction, they can cause damaging effects on many of the
technologies that we rely on in our everyday lives, such as communications
satellites and mobile phone networks.

The Solar atmosphere, observed in ultraviolet light by the Solar Dynamics Observatory Atmospheric Imaging Assembly. Observations from SDO form part of the analysis in this research.

Credit: NASA/SDO

Despite decades of study, the precise link between coronal
mass ejections and a range of other phenomena including radio bursts of several
kinds and ultraviolet pulses has remained unclear. However a new study bringing
together researchers in Ireland, the US and UCL Mullard Space Science
Laboratory’s David Long, has shed new light on the matter, suggesting that
these phenomena share a common cause: huge shock waves in the solar atmosphere,
which are driven by coronal mass ejections.

“This was a really unique set of observations which providesa new insight into how these phenomena are related,” says Long.

The team’s work was based in part on space-based
observations from NASA’s Stereo and Solar Dynamics Observatory probes.
Alongside this, the team established a radio observatory in Birr Castle in
Ireland, site of a historic observatory of the late 19th century, to
monitor the solar radio bursts.

The findings, which were published online this week in
Nature Physics, show that coronal mass ejections create huge shock waves that race
through the solar atmosphere at millions of kilometres per hours. As they do,
they can accelerate electrons to huge energies, which then produce radio waves.
Long’s contribution to the study was to examine the nature of these shock
waves.

The results of the group’s study not only give an insight
into the fundamental physics of massive explosions on the Sun, but enable us to
better understand how the Sun affects the Earth and potentially its impacts on
our daily lives.

Notes

The research appears in a paper published in the journal Nature Physics , entitled "Quasiperiodic acceleration of electrons by a plasmoid-driven shock in the solar atmosphere"